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A062919
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"Reverse factorials": product of the digit reversals of the numbers 1 through n.
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2
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1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 362880, 3991680, 83825280, 2598583680, 106541930880, 5433638474880, 331451946967680, 23533088234705280, 1906180147011127680, 173462393378012618880
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OFFSET
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0,3
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COMMENTS
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How many trailing zeros are there in a(n)?
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LINKS
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FORMULA
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EXAMPLE
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a(11) = 3991680 = 1*2*3*4*5*6*7*8*9*R(10)*R(11) = 1*2*3*4*5*6*7*8*9*1*11.
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MATHEMATICA
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FoldList[Times, 1, Table[FromDigits[Reverse[IntegerDigits[n]]], {n, 20}]] (* Harvey P. Dale, Aug 20 2012 *)
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PROG
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(PARI) Rev(x)= { local(d); r=0; while (x>0, d=x-10*(x\10); x\=10; r=r*10 + d); return(r) } { for (n=0, 100, if (n, a*=Rev(n), a=1); write("b062919.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 13 2009
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CROSSREFS
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KEYWORD
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base,nonn,easy
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AUTHOR
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EXTENSIONS
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More terms from Lior Manor and Larry Reeves (larryr(AT)acm.org), Jul 05 2001
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STATUS
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approved
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